1. Field of the Invention
The present invention relates to devices for displaying images, and more particularly, to a device for generating planar light and an image display device having the planar light generating device.
2. Description of the Related Art
Liquid crystal display (LCD) devices are one of the types of the image display devices. Since the LCD devices have advantageous properties such as small thickness, low driving voltage, low power consumption, etc., they have been widely used for displaying images.
The LCD devices display images using liquid crystal, and it is necessary to externally provide light to the liquid crystal in an LCD device. Accordingly, the LCD devices generally have a backlight assembly to generate light to the liquid crystal.
Conventional backlight assemblies include a cold cathode fluorescent lamp (CCFL) having a tubular shape. The CCFLs may be classified into edge illumination type CCFLs and direct illumination type CCFLs. In an LCD device employing the edge illumination type CCFL(s), one or two edge illumination type CCFLs are disposed on edge portions of a light guide plate having a reflecting layer so as to supply light to an LCD panel. In an LCD device employing the direct illumination type CCFL, the direct illumination type CCFL is disposed under the light guide plate. A reflection plate and a diffusion plate are disposed under the direct illumination type CCFL and on the light guide plate, respectively, so as to supply light to an LCD panel.
A conventional backlight assembly includes optical members, such as the light guide plate or the diffusion plate, so that the optical members absorb a portion of the light. As a result, luminance of the light generated from the backlight assembly is decreased. Also, uniformity of the luminance is decreased. In addition, since the conventional backlight assemblies have a complex structure, their manufacturing cost increases.
Planar light generating devices have been developed to solve the above mentioned problems. The planar light generating devices generally include a body and electrodes. The body includes discharge spaces disposed adjacent to one another. A discharge voltage is applied to the body through the electrodes. The discharge spaces are connected to one another so that distribution of a discharge gas in the discharge spaces may be uniformized. The discharge voltage is applied to the electrodes to form a plasma discharge in the discharge spaces, thereby generating the light.
When the plasma discharge is formed in the discharge spaces, current may flow through the discharge spaces so that a voltage drop is formed in each of the discharge spaces. The amount of the voltage drop is substantially equal to the current multiplied by a square of a resistance of each of the discharge spaces. The resistances of the discharge spaces are different from one another, so that the voltage drops of the discharge spaces are different from one another. The difference between the voltage drops form a potential difference between the discharge spaces, so that a portion of the current may be concentrated on one of the discharge spaces, thereby forming a channeling of the current. The channeling of the current deteriorates the luminance, and the uniformity of the luminance may also be decreased. As a result, image display quality of the LCD device is lowered.